/*
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*
 *    ASSearch.java
 *    Copyright (C) 1999 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.attributeSelection;

import weka.core.Instances;
import weka.core.RevisionHandler;
import weka.core.RevisionUtils;
import weka.core.SerializedObject;
import weka.core.Utils;

import java.io.Serializable;

/**
 * Abstract attribute selection search class.
 * 
 * @author Mark Hall (mhall@cs.waikato.ac.nz)
 * @version $Revision: 1.12 $
 */
public abstract class ASSearch implements Serializable, RevisionHandler {

	/** for serialization */
	private static final long serialVersionUID = 7591673350342236548L;

	// ===============
	// Public methods.
	// ===============

	/**
	 * Returns the revision string.
	 * 
	 * @return the revision
	 */
	public String getRevision() {
		return RevisionUtils.extract("$Revision: 1.12 $");
	}

	/**
	 * Searches the attribute subset/ranking space.
	 * 
	 * @param ASEvaluator
	 *            the attribute evaluator to guide the search
	 * @param data
	 *            the training instances.
	 * @return an array (not necessarily ordered) of selected attribute indexes
	 * @throws Exception
	 *             if the search can't be completed
	 */
	public abstract int[] search(ASEvaluation ASEvaluator, Instances data)
			throws Exception;

	/**
	 * Creates a new instance of a search class given it's class name and
	 * (optional) arguments to pass to it's setOptions method. If the search
	 * method implements OptionHandler and the options parameter is non-null,
	 * the search method will have it's options set.
	 * 
	 * @param searchName
	 *            the fully qualified class name of the search class
	 * @param options
	 *            an array of options suitable for passing to setOptions. May be
	 *            null.
	 * @return the newly created search object, ready for use.
	 * @throws Exception
	 *             if the search class name is invalid, or the options supplied
	 *             are not acceptable to the search class.
	 */
	public static ASSearch forName(String searchName, String[] options)
			throws Exception {
		return (ASSearch) Utils.forName(ASSearch.class, searchName, options);
	}

	/**
	 * Creates copies of the current search scheme. Note that this method now
	 * uses Serialization to perform a deep copy, so the search object must be
	 * fully Serializable. Any currently built model will now be copied as well.
	 * 
	 * @param model
	 *            an example search scheme to copy
	 * @param num
	 *            the number of search scheme copies to create.
	 * @return an array of search schemes.
	 * @throws Exception
	 *             if an error occurs
	 */
	public static ASSearch[] makeCopies(ASSearch model, int num)
			throws Exception {

		if (model == null)
			throw new Exception("No model search scheme set");

		ASSearch[] result = new ASSearch[num];
		SerializedObject so = new SerializedObject(model);
		for (int i = 0; i < result.length; i++)
			result[i] = (ASSearch) so.getObject();

		return result;
	}
}
